Dual-drive modulator

Abstract

A transmitter module includes a processor configured to receive input data, and determine input values corresponding to the input data; a digital-to-analog converter configured to receive the input values from the processor, and generate first and second voltage signals based on the input values; a laser configured to output light; a Mach-Zehnder modulator configured to receive the light from the laser and the first and second voltage signals from the digital-to-analog converter, and modulate the light based on the first and second voltage signals to generate a modulated optical signal that includes distortion; and a filter configured to receive the modulated optical signal from the modulator, process the modulated optical signal to reduce or eliminate the distortion and produce an output optical signal, and output the output optical signal.

What is claimed is: 
     
       1. An optical system, comprising:
 a transmitter module comprising: 
 a processor configured to:
 receive input data, and 
 determine input values corresponding to the input data; 
 
 a digital-to-analog converter configured to:
 receive the input values from the processor, and 
 generate first and second voltage signals based on the input values; 
 
 a laser configured to output light; 
 a Mach-Zehnder modulator configured to:
 receive the light from the laser and the first and second voltage signals from the digital-to-analog converter, and 
 modulate the light based on the first and second voltage signals to generate a modulated optical signal that includes distortion; and 
 
 a filter configured to:
 receive the modulated optical signal from the modulator, 
 process the modulated optical signal to reduce or eliminate the distortion and produce an output optical signal, and 
 output the output optical signal, 
 
 where the digital-to-analog converter is a first digital-to-analog converter, the first digital-to-analog converter being configured to: 
 receive a first set of the input values from the processor, and 
 generate the first and second voltage signals based on the first set of input values, 
 the transmitter module further comprising: 
 a second digital-to-analog converter configured to: 
 receive a second set of the input values from the processor, and 
 generate third and fourth voltage signals based on the second set of the input values, where the modulator is a first modulator, the first modulator being configured to: 
 receive a first portion of the light from the laser and the first and second voltage signals from the first digital-to-analog converter, and 
 modulate the first portion of the light based on the first and second voltage signals to produce a first modulated optical signal; 
 the transmitter module further comprising: 
 a second modulator configured to: 
 receive a second portion of the light from the laser and the third and fourth voltage signals from the second digital-to-analog converter, and 
 modulate the second portion of the light based on the third and fourth voltage signals to produce a second modulated optical signal, 
 where the transmitter module further comprises: 
 
       a combiner configured to: 
       receive the first modulated optical signal and the second modulated optical signal, and 
       combine the first modulated optical signal and the second modulated optical signal to produce the output optical signal, and 
       where the combiner is further configured to reduce or eliminate the distortion from the first modulated optical signal or the second modulated optical signal. 
     
     
       2. The optical system of  claim 1 , where the modulator includes:
 a splitter configured to: 
 receive the light from the laser, and 
 split the light into a first portion of light and a second portion of light; 
 a first waveguide configured to: 
 receive the first portion of the light and the first voltage signal, and 
 modulate the first portion of the light based on the first voltage signal to produce a first modulated signal with first distortion; 
 a second waveguide configured to: 
 receive the second portion of the light and the second voltage signal, and 
 modulate the second portion of the light based on the second voltage signal to produce a second modulated signal with second distortion; and 
 a combiner configured to: 
 receive the first modulated signal and the second modulated signal, 
 combine the first modulated signal and the second modulated signal to produce the modulated optical signal, and 
 output the modulated optical signal. 
 
     
     
       3. The optical system of  claim 1 , where the processor, when determining the input values, is configured to:
 convert the input data to symbols at a first rate, 
 apply a pulse shape calculation to the symbols, and 
 calculate, after applying the pulse shape calculation to the symbols, the input values at a second rate, the second rate being greater than or equal to the first rate. 
 
     
     
       4. The optical system of  claim 1 , where the processor is further configured to:
 convert the input data to constellation points on a complex plane, and 
 determine a pulse shape that defines transitions between the constellation points. 
 
     
     
       5. The optical system of  claim 1 , where the transmitter module further comprises:
 a splitter configured to: 
 receive the light from the laser, 
 split the light into the first portion of the light and the second portion of the light, 
 output the first portion of the light to the first modulator, and 
 output the second portion of the light to the second modulator. 
 
     
     
       6. The optical system of  claim 1 , where the first modulated optical signal has a first polarization and the second modulated optical signal has a second polarization, the second polarization being substantially orthogonal with respect to the first polarization. 
     
     
       7. An optical system comprising:
 a transmitter module comprising: 
 a processor configured to:
 receive input data, and 
 determine input values corresponding to the input data; 
 
 a digital-to-analog converter configured to:
 receive the input values from the processor, and 
 generate first and second voltage signals based on the input values; 
 
 a laser configured to output light; 
 a Mach-Zehnder modulator configured to:
 receive the light from the laser and the first and second voltage signals from the digital-to-analog converter, and 
 modulate the light based on the first and second voltage signals to generate a modulated optical signal that includes distortion; and 
 
 a filter configured to:
 receive the modulated optical signal from the modulator, 
 process the modulated optical signal to reduce or eliminate the distortion and produce an output optical signal, and 
 output the output optical signal, 
 where the processor is one of a plurality of processors, each of the plurality of processors being configured to: 
 receive respective input data, and 
 determine respective input values corresponding to the respective input data, 
 where the digital-to-analog converter is one of a plurality of digital-to-analog converters, each of the plurality of digital-to-analog converters being configured to: 
 receive the respective input values from a corresponding one of the plurality of processors, and 
 generate respective first and second voltage signals based on the respective input values, 
 where the laser is one of a plurality of lasers configured to output light, 
 where the modulator is one of a plurality of first modulators or one of a plurality of second modulators, each of the plurality of first modulators being configured to: 
 receive the respective light from a corresponding first one of the plurality of lasers and the respective first and second voltage signals from a corresponding first one of the plurality of digital-to-analog converters, and 
 modulate the respective light, from the corresponding first one of the plurality of lasers, based on the respective first and second voltage signals, from the corresponding first one of the plurality of digital-to-analog converters, to produce a first modulated optical signal; 
 each of the plurality of second modulators being configured to: 
 receive the respective light from a corresponding second one of the plurality of lasers and the respective first and second voltage signals from a corresponding second one of the plurality of digital-to-analog converters, and 
 modulate the respective light, from the corresponding second one of the plurality of lasers, based on the respective first and second voltage signals, from the corresponding second one of the plurality of digital-to-analog converters, to produce a second modulated optical signal, and 
 
 where the transmitter module further comprises: 
 a first arrayed waveguide grating configured to: 
 receive the first modulated optical signals, and 
 combine the first modulated optical signals to produce a first combined optical signal; 
 a second arrayed waveguide grating configured to: 
 receive the second modulated optical signals, and 
 combine the second modulated optical signals to produce a second combined optical signal; and 
 a combiner configured to: 
 receive the first combined optical signal and the second combined optical signal, and 
 combine the first combined optical signal and the second combined optical signal to provide the output optical signal. 
 
     
     
       8. The optical system of  claim 7 , where the transmitter module further comprises:
 a combiner configured to: 
 receive the first modulated optical signals and the second modulated optical signals, and 
 combine the first modulated optical signals and the second modulated optical signals to provide the output optical signal. 
 
     
     
       9. A transmitter module, comprising:
 a plurality of transmitter components configured to produce a plurality of first modulated signals and a plurality of second modulated signals; 
 a first combiner configured to receive the plurality of first modulated signals and combine the plurality of first modulated signals into a first combined signal; 
 a second combiner configured to receive the plurality of second modulated signals and combine the plurality of second modulated signals into a second combined signal; and 
 a third combiner configured to combine the first combined signal and the second combined signal into an output optical signal and output the output optical signal, one of the plurality of transmitter components including: 
 a processor configured to: 
 receive input data, and 
 determine a first set of input values and a second set of input values corresponding to the input data; 
 a first digital-to-analog converter configured to: 
 receive the first set of input values from the processor, and 
 generate first and second voltage signals based on the first set of input values; 
 a second digital-to-analog converter configured to: 
 receive the second set of input values from the processor, and 
 generate third and fourth voltage signals based on the second set of input values; 
 a first Mach-Zehnder modulator configured to: 
 receive first light and the first and voltage signals from the first digital-to-analog converter, and 
 modulate the first light based on the first and second voltage signals to produce one of the plurality of first modulated signals that includes distortion; and 
 a second Mach-Zehnder modulator configured to: 
 receive second light and the third and fourth voltage signals from the second digital-to-analog converter, and 
 modulate the second light based on the third and fourth voltage signals to produce one of the plurality of second modulated signals that includes distortion; 
 the first combiner being further configured to reduce or eliminate the distortion from the one of the plurality of first modulated signals; 
 the second combiner being further configured to reduce or eliminate the distortion from the one of the plurality of second modulated signals. 
 
     
     
       10. The transmitter module of  claim 9 , where the plurality of first modulated signals have a first polarization, and the plurality of second modulated signals have a second polarization, the second polarization being substantially orthogonal with respect to the first polarization. 
     
     
       11. The transmitter module of  claim 9 , where the one of the plurality of transmitter components further includes:
 a laser configured to output light; and 
 a splitter configured to: 
 receive the light from the laser, 
 split the light into the first light and the second light, 
 output the first light to the first modulator, and 
 output the second light to the second modulator. 
 
     
     
       12. The transmitter module of  claim 9 , where the processor is further configured to:
 apply forward error correction to the input data to provide forward error correction encoded data, or 
 
       apply timing skew to the input data to provide timing-skewed data.